In the current Integrated Digital Enhanced Network (iDEN) technology, a subscriber unit will perform International Mobile Equipment Identifier (IMEI) registration in order to obtain its International Mobile Subscriber Identifier (IMSI) under two scenarios: during initial power-up of the subscriber unit when it does not have an IMSI; and when the subscriber unit has been configured to perform a master reset, which will result in the subscriber unit not having an IMSI.
If a subscriber unit has not successfully performed IMEI registration, it will not have an IMSI and it will not be able to perform any iDEN-related services, such as dispatch, interconnect, and packet data transfer. There are typically two different scenarios when an iDEN subscriber unit fails IMEI registration with the iDEN network—when the subscriber unit's IMEI is not provisioned on the iDEN carrier's network and when there is a network failure.
When a network failure occurs, the iDEN network (i.e., DAP and/or HLR) sends a NETWORK_FAILURE message to the subscriber unit. In this scenario, the iDEN subscriber unit will scan its bandmap to find an iDEN cell site or iDEN network that may accept its IMEI registration, and then retry the IMEI registration approximately 25–35 seconds later. The iDEN subscriber unit will continue to retry the IMEI registration procedure every 25–35 seconds thereafter, provided that it continues to receive a NETWORK_FAILURE message from the iDEN network. In the case of a large number of users all trying IMEI registration every 25–35 seconds without success, this can cause a dramatic increase in the amount of (needless) network traffic over the system. Thus, there is a need for a system and method which overcomes the aforementioned drawbacks to the IMEI registration process.